This invention relates to a method and apparatus for the simultaneous printing of graphic forms data and information data by dot matrix printers, such as laser-xerographic printers, used as output devices for data processing systems.
It is sometimes desirable to print information data from a data processing source on a company, governmental or graphic form. In the past, this has required that the forms be printed first and then aligned on the printer to have the printed data appear in the correct locations on the form. However, the use of preprinted forms instead of blank paper proved to be expensive, and alternate approaches were developed whereby graphic forms could be overlayed optically on the information data as it was being printed. One such approach, called the forms flash approach for use with laser-xerographic printers, transmits light through a transparency of the desired forms pattern onto an optical system which directs the transmitted light onto the printer's photo-conducting drum. However, the light source and optics in the forms flash method generally provides print of different intensity and resolution than the print provided by the laser light source resulting in different shades of print on the final output copy. In addition, in the forms flash system, the forms drum must be almost as large as the actual form, hence, the forms flash devices are bulky, primarily optomechanical in nature, sensitive to adjust, and moderately expensive.